JPH05509362A - Chemical pulp bleaching method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] How to bleach chemical valves The present invention relates to a method for bleaching chemical valves, which includes at least one bleaching step and a few bleaching steps. Bleaching consisting of at least one alkaline treatment step and treatment of the valve with enzymes Regarding the method.

In particular, chemical compounds obtained by sulfate cooking Bulbs take on a brown color mainly due to the lignin remaining in the bulbs.

Lignin is removed by bleaching, which is usually treated with an oxidizing agent that breaks down the lignin. and a process of treating the decomposition products produced by the decomposition with chemicals that dissolve them. This is done through a multi-stage process that is performed alternately. The most commonly used oxidizing agents are chlorine-containing therefore, alkaline solutions are used as chemicals to remove decomposition products. be done.

During the reaction, the chlorine-containing bleach converts the lignin in the bulb into organochlorine compounds, This enters the bleach waste solution that is removed from the valve. Put the bleach waste in it. The highly toxic organic chlorine compounds introduced into the environment cause environmental problems, and bleach waste The chemical oxygen consumption of the liquid is high and harmful.

Bleach waste, which causes environmental pollution, undergoes initial chlorination and initial alkaline treatment of the bleaching solution. This occurs during the cleaning process after the carini stage. To reduce this environmental pollution, for example, chlorine For example, replacing the gas with chlorine dioxide or using oxygen as an oxidizing agent in the first step. Various efforts have been made in this way. However, these methods are still not fully satisfactory. The desired results have not been obtained. Chlorophenols and other toxic chlorine compounds in wastewater Efforts to reduce the amount of effluent have certainly been successful; It was not possible to achieve this goal. Therefore, effective use of biological purification is needed to support the above method. It is necessary to use

Recent research has shown that the use of enzymes to assist in bleaching can Separate lignin and/or hemicellulose from loin and in this way It has been found that the manufactured valves can be easily bleached in a subsequent bleaching step. centre According to Reims Patent No. 881192, balm bleached using chlorine compounds The amount of residual chlorine in the water can be reduced by enzymatic treatment. In this case, the enzyme treatment It is disclosed what should be carried out before or after the oxidation and alkalinization steps for bleaching. ing.

The purpose of the present invention is to provide a new method for enzymatic treatment of valves. This method reduces the amount of chemicals needed for bleaching and at the same time reduces the chemical acidity of bleach waste. Valve in a way that reduces elemental consumption and toxicity, and also reduces the amount of water required for purification. can be bleached. A feature of the invention is that the bulb can be bleached in two or more ways. In each enzyme treatment process, the valve is placed immediately before the enzyme treatment. Processing that is substantially different from the step or the step immediately following is performed.

According to the invention, the action of the enzyme is carried out in several different steps, preferably in its process. When used between the oxidation process and the alkaline process belonging to the observed. Enzymatic treatment at the beginning of the bleaching process reduces the use of chlorine-containing chemicals. It was observed that the dose could be reduced by about 25%.6 Therefore, the enzyme treatment according to the present invention was repeated. By recycling, the amount of chemicals needed for bleaching can be significantly reduced.

The preferred number of enzyme treatment steps in the bleaching method of the present invention is 2 to 4 steps. . A preferred method includes three enzyme treatment steps, followed by 2. Adjust to the ratio of Ox Kafupa number did. The treatment temperature was 40° C., the treatment time was 45 minutes, and the pulp content was 3.5%.

The pulp is then anointed using a 2% sodium hydroxide solution with a ratio of 0.9x Kafpa. Lucari treated. The consistency of the mixture was 10%, the treatment temperature was 60℃, and the treatment The time was 90 minutes. After the alkali treatment, the pulp was washed with 20 times more water.

This was followed by an enzymatic step using the same enzyme mixture as the first step, followed by an enzymatic step using chlorine dioxide. The oxidation step and the cleaning between the steps were repeated. In this case, the second fermentation The amount of enzyme in the raw treatment was 2.50/g (pulp). Dioxide salt from the second oxidation step The amount of base material was 1.5% of the amount of pulp to be bleached.

The bleached pulp was analyzed and the results are shown in Table 1 below.

In addition to the above experiment (Experiment 2) and explanation, a comparative experiment (Experiment 1) was conducted, and the results are also shown in Table 1 below.

The experiment was conducted as follows.

Experiment 1 (comparative experiment): The second enzyme treatment of the valve was not performed.

Other points are the same as those described above (Experiment 2).

Table 1 Experiment 1 Experiment 2 (Comparative example) 1st enzyme treatment (enzyme ratio n/l) 1 1C7!0□/C1 ratio 50150 50150 Kappa 27.7 27.7H Enzyme process 5.4 5.6 Oxidation step (C10□/CI) 2.1 2.1 Alkalinity 11.7 11. 6 Active chlorine consumption (%) 5.54 5.54 Medium kappa 5.7 5.7 2nd enzyme treatment (1/l) 0.5 H Second enzyme treatment 5.3 Oxidation step (Color) 2.1 2. ISO□Process Start/End 4.8/3 ．． 7 4.8 / 3.7 Whiteness 60.97 67.54 Those skilled in the art will appreciate that the various embodiments of the invention are not limited to the above-described examples; It will be obvious that modifications may be made within the scope of the appended claims.

Summary book The present invention relates to a method for bleaching chemical pulp, comprising one or several oxidation steps, one or relates to a bleaching method involving several alkaline treatment steps and the treatment of pulp with enzymes. Book The principle of the invention is to treat with enzymes in two or more steps during the process, and Oxidation and/or alkaline treatment is carried out between the treatment steps. use A particularly preferred oxidizing agent is oxygen, but in addition or in place of Hydrogen oxide and/or chlorine and/or chlorine dioxide may be used. Wear. In addition, it is preferable to perform the enzyme treatment step 2 to 4 times, but it is preferable to perform the enzyme treatment step 2 to 4 times. The different enzymes mentioned above can also be used alternately. By the enzyme treatment of the present invention, The amount of toxic chlorine compounds in bleaching effluents is reduced, while the chemical oxygen consumption of the effluents is also reduced. Decrease.

international search report international search report 1 Special Table Sen5-509362 (4)

Claims (10)

[Claims] (1) At least one oxidation process, at least one alkali treatment process, and pulp treatment with enzymes. A method of bleaching chemical pulp comprising: treating the pulp during the bleaching process; is treated with enzymes in two or more steps, and the pulp is treated with enzymes during each enzyme treatment step. characterized by employing a method that is substantially different from the process step immediately before or after bleaching method. (2) The bleaching method of claim 1, which comprises 2 to 4 separate enzyme treatment steps. (3) The bleaching method of claim 2, which comprises three separate enzyme treatment steps. (4) The first step in the bleaching process is enzymatic treatment of the pulp, and the next step is the use of an oxidizing agent. oxidation of the pulp, a second enzyme treatment, a treatment with an alkali and a third enzyme treatment. and then one or several oxidation and/or alkali treatments 4. The bleaching method according to claim 3, wherein the bleaching process continues. (5) Claims in which the oxidizing agent used in one or several processes or steps is oxygen. The bleaching method according to any one of paragraphs 1 to 4. (6) During the process, after at least one enzymatic treatment step, acid to alkali Claim 1: Alkaline treatment is carried out by adding an oxidizing agent such as hydrogen peroxide or hydrogen peroxide. The bleaching method according to any of Items 5 to 5. (7) The first step in the process is enzymatic treatment, and the next step is oxidation with an oxidizing agent. 2. Enzyme treatment, alkaline treatment with oxygen or hydrogen peroxide added to alkali, 3. enzymatic treatment, oxidation with oxygen or chlorine dioxide, alkali treatment, and is sequentially oxidized with chlorine dioxide according to any one of claims 4 to 6. bleaching method. (8) The enzymes used are hemicellulase, cellulase, pectinase, and esterase. ligninase and/or phenol oxidase. The bleaching method according to any one of Items 1 to 7. (9) includes at least two separate enzymatic treatments, in which at least two different enzymes are used; A bleaching method according to any one of claims 1 to 8. (10) The above process can be applied to pulp obtained from softwood such as pine sulfate pulp. A bleaching method according to any one of claims 1 to 9 applied to bleaching.